Surface restoration in hygroscopic VI3 crystals via synchrotron soft X-ray irradiation

TL;DR

This study demonstrates that synchrotron soft X-ray irradiation can partially restore the chemical and electronic properties of hygroscopically degraded VI3 van der Waals crystals, offering a potential method for surface recovery.

Contribution

It introduces a novel approach using synchrotron soft X-ray irradiation to recover surface properties of VI3 crystals degraded by environmental exposure.

Findings

Soft X-ray irradiation partially restores VI3 surface stoichiometry.

Degradation involves formation of vanadates on the surface.

Hygroscopic contamination couples weakly to the crystal surface.

Abstract

Among van der Waals crystals, transition metal trihalide VI3 has driven attention for its magnetic and orbital properties. However, its chemical instability under ambient conditions make its exploitation challenging for technological implementation. In this context, here we show how synchrotron radiation soft X-rays partially restore stoichiometric chemical and electronic properties of VI3 crystals. By combining X-ray absorption and X-ray photoemission spectroscopies, we show as-cleaved and aged (in ultra-high vacuum conditions) chemical degradation of VI3 crystal surface, with the formation of vanadates, and its, at least partial, recovery under high-flux soft X-ray beam exposure, revealing that superficial hygroscopic contamination couples relatively weakly to the crystal surface.